There is great interest today in technologies that support ‘virtual reality’ (VR), including display and manipulation of virtual objects. Recent advances in VR have been driven in part by the emergence of low-cost, stereoscopic near-eye display devices and machine-vision systems. Once limited to high-end gaming, VR is now making significant inroads in other areas, such as engineering design and productivity. An ongoing goal in VR research and development is to continue to improve display, tracking, and manipulation modalities, so that virtual objects take on a real-life quality in terms of appearance and manner of manipulation.